Plate clamp

ABSTRACT

A plate clamp to detachably secure a printing plate on a plate cylinder of a printing press comprising a row of spaced pegs positionable through spaced apertures formed adjacent the leading edge of a printing plate, and a row of spaced pins secured to a shaft mounted for rotation to position the pins through apertures formed adjacent the trailing edge of the plate. The shaft is urged by a spring to a position wherein the plate is positively located and tightly drawn about a portion of the circumference of the plate cylinder.

United States Patent 1 1 1111 3,874,292 Parsley Apr. 1, 1975 15 PLATECLAMP 3,727,551 4/1973 Kostas et a1. 101/415.1 Inventor: Robert L. y,Dallas, Tex- 3.766,857 10/1973 Schlatter 101/415.1 [73] Assignee:Dahlgren Manufacturing Company, Primary Examiner-Stephen C. PellegrinoInc., Dallas, Tex. Attorney, Agent, or Firm-Howard E. Moore; Gerald 22Filed: Sept. 17, 1973 [21] Appl. No.: 397,898 [57] ABSTRACT A plateclamp to detachably secure a printing plate on [52 [1,5, c 101 4154, 0137 101 332 :1 plate cylinder ofa printing press comprising a row of 51m, 3 B41f27/12 spaced pegs positionable through spaced apertures 53Fie|d f Search 101 4151 37 332 33 formed ad acent the leadmg edge of aprmting plate, 101 379 and a row of spaced pms secured to a shaftmounted for rotation to position the pins through apertures 5 ReferencesCited formed adjacent the trailing edge of the plate. The UNITED STATESPATENTS shaft is urged by a spring to a position wherein the a 7 7 Iplate is positively located and tightly drawn about a l gggg 16 529portion of the circumference of the plate cylinder. 3.381799 5/1968Luers l01/415.l 6 Claims, 9 Drawing Figures PLATE CLAMP BACKGROUND OFTHE INVENTION Lithographic printing plates are generally constructed ofthin, flexible metal and have flanges formed on leading and trailingedges thereof. The flange on the leading edge of the plate is generallyinserted into a groove or slot formed in the plate cylinder and thetrailing edge has been secured by various forms of clamping devices.

For example, US. Pat. No. 3,533,355 discloses a clamping member having arow of set screws extending therethrough to permit adjustment of theedge of the clamping member circumferentially about a plate cylinder.

Another type of mechanism for clamping plates to plate cylinders in aprinting press is illustrated in US. Pat. No. 3,058,417 in whichopposite edges of the printing plate are clamped prior to tensioning theprinting plate by inflating a rubber tube.

Plate clamps heretofore devised required use of tools for tighteningscrews or bolts to secure a plate clamp in position and requiredsubstantial time for changing plates and making the press ready toprint.

SUMMARY OF INVENTION I have devised an improved plate clamp comprising ashaft having outwardly extending projections or pins spaced along thelength thereof positionable through apertures formed along the trailingedge of a printing plate.

For attaching a plate to a printing cylinder projections or pegs on theprinting cylinder are positioned through apertures adjacent the leadingedge of the printing plate. The plate is then wrapped around inportion'of the circumference of the printing cylinder and aperturesadjacent the trailing edge of the printing plate are positioned over theprojections on the rotatable shaft. A spring on the shaft urges theprojections to a position wherin the printing plate is properlytensioned.

The shaft is manually rotated to permit removal of the printing plate.

The improved plate clamp is attached to a saddle conncctablc to thecylinder of a letter press for example, of the type employed forprinting newspapers, to expeditiously convert a letter press forlithographic printing.

A primary object of the invention is to provide a plate clamp adjacentto positively engage edges of a printing plate and to automatically drawthe plate to a predetermined tension.

Another object of the invention is to provide a plate clamp resilientlydrawing a printing plate to a predetermined tension by application of asubstantially constant force adjacent the trailing edge of the printingplate.

A further object of the invention is to provide a saddle for convertinga letter press to a lithographic printing press wherein each of thesaddles'has a spring urged plate clamp mechanism secured theretopermitting attachment'of the saddle and plate clamp to a cylinder of theletter press.

Other and further objects of the invention will become apparent uponreferring to the detailed description hereinafter following and to thedrawings annexed hereto.

DESCRIPTION OF THE DRAWING Drawings of a preferred embodiment of theinvention are annexed hereto so that the invention may be better andmore fully understood, in which:

FIG. I is an end view of a printing cylinder having a pair of saddlessecred thereto, each saddle having plate clamps incorporated therein;

FIG. II is a perspective view of a saddle;

FIG. III is a fragmentary exploded perspective view of a saddle andplate clamp;

FIG. IV is an enlarged fragmentary elevational view of the plate clampillustrated in FIG. I;

FIG. V is a cross-sectional view taken along lines VV of FIG. IV;

FIG. VI is a cross-sectional view taken along the lines VIVI of FIG. V;

FIG. VII is a cross-sectional view taken along the line VII-VII of FIG.V;

FIG. VIII is a cross-sectional view taken along line VIII-VIII of FIG.V; and

FIG. IX is a fragmentary cross-sectional view similar to FIG. VIIIillustrating a method of rotating the plate clamp for engaging ordisengaging a printing plate.

Numeral references are employed to designate like parts throughout thevarious figure of the drawing.

PREFERRED EMBODIMENT Referring to FIG. I of the drawing, the number 1generally designates a printing cylinder having journals 2 adjacentopposite ends thereof rotatable in a bearing (not shown).

Saddles 4 and 6 are of identical construction having leading edges 4aand 6a and trailing edges 4 b and 6b respectively. The concave sides 4cand 6c of the respective saddles have notches 6d formed therein, as bestillustrated in FIGS. II and III, to receive lugs on cylinder 1 securingthe saddles to the plate cylinder.

As best illustrated in FIG. II, the leading edge 6a of saddle 6 has pegs8 extending outwardly therefrom to extend through apertures 310a formedin a deflected flange 12a adjacent leading edge of printing plate 15.

As best illustrated in FIG. III the trailing edge 6b of saddle 6 has asemi-circular seat 16 formed therein. Sockets 18 are formed in oppositeends of seat 16 to receive pin 20 on hinge element 22. Pin 20 has anaper ture 20a extending transversely therethrough to receive a dowel 24when positioned in hole 18:! extending through the edge 6b of saddle 6and intersecting socket l8.

Hinge element 22 has a lug 26 formed thereon positioned to engageshoulder 28 on a tail stop comprising elongated rectangular bar 30extending longitudinally through gap 32 formed in a surface of cylinder1 of the compression lock-up type.

As best illustrated in FIGS. III and V, hinge element 22 has a bore 32extending therethrough to receive the journal 34 on the end of shaft 36.Opposite ends of shaft 36 have reduced diameter portions 38 formedthereon to provide shoulders 40 and 42 adjacent each end thereof. Itshould be appreciated that the bore 32 through hinge element 22 receivesjournal 34 on the end of shaft 36 while shoulder 42 in maintained inabutting relation with hinge element 22 preventing longitudinal movementof shaft 36 relative to saddles 4 and 6.

Hinge element 22 has a hole 44 formed therein to receive end 46 of coilspring 48. The opposite end 50 of bolts as has been coil spring 48extends into a hole 52 formed in shoulder 40 on shaft 36.

Connector means such as pins 58 extend into spaced apertures b formed inflange 12b of printing plates 14 and 15. Rotation of shaft 36 is limitedby stop pin 65 secured to saddle 4 and positioned in slot 66 formed inshaft 36.

The operation and function of the apparatus hereinbefore described is asfollows:

Saddles 4 and 6 are attached to cylinders 1 in the same manner andemploying conventional connector lugs heretofore employed for attachingletter press plates to a printing cylinder. Either compression ortension lock-up devices may be employed.

After saddles 4 and 6 have been connected to cylinder-1 printing plateis connected about the outer surface of saddle 6 by positioningapertures 10a extending through flange 12a adjacent the leading edge ofplate 15 about pegs 8. Tool T is inserted in opening 60 formed in acentral portion of shaft 36 and shaft 36 is rotated to the positionillustrated in the dashed outline in FIG. IX. Pins 58 are positionedthrough apertures 10b extending through flange 12b adjacent the trailingedge of plate 15. When tool T is released springs 48 will urge shaft 36to the position illustrated in full outline in FIG. IX drawing the plateto a predetermined tension established by the spring; constant ofsprings 48.

Plates 14 and 15 can be removed by positioning tool T through the slot12c in the central portion of flange 12!) into opening 60 and rotatingshaft 36 to the position illustrated in the dashed outline in FIG. lX.

From the foregoing it should be readily apparent that printing platescan be quickly and accurately position'ed about the surface of theprinting cylinder without necessitating'loosening and tightening ofscrews or heretofore required for securing plate clamps. I

While the plate clamp hereinbefo'redescribed has been illustrated incombination with a's'addlc for adapting a letter press to a lithographicprinting press, it should be appreciated that the plate clamp structurecan be connected directly to the plate cylinder of a lithographicprinting press adjacent opposite sides of a gap extendinglongitudinallythereof. It should further be appreciated that the plate clamphercinbefore described is sufficiently compact to be employed in webpresses wherein the printing plate extends about substantially all ofthe circumference of the plate cylinder.

While the embodiment ofthe invention hereinbefore describedandillustrated in the attached drawing is a preferred embodiment of theinvention, other and further embodiments of the invention may be devisedwithout departing from the basic concept thereof.

Having described my invention, 1 claim;

, 1.,Apparatus to secure a printing plate having aperturesformedinflanges on leading and trailing edges.

4 ient means being adapted to urge the connector pins on the shaftinto'the gap 'formedin' the cylinder.

2. The combination called for in claim 1 wherein the means to rotatablysecure the shaft to the cylinder comprises: a hinge element having abore extending therethrough; and means to secure said hinge element tothe cylinder, and wherein the shaft has ajournal formed on the endthereof; a shoulder adjacent said journal, said journal being positionedin the bore in the hinge element such that the shoulder on the shaftengages said hinge element to limit longitudinal movement on the shaftrelative to hinge element.

3. Apparatus to secure a printing plate to a cylinder having alongitudinally extending gap formed therein comprising: means to securea first edge of a printing plate adjacent a first edge of the gap formedin the cylinder; a shaft; connector meansI to secure a second edge of aprinting plate to said shaft; a saddle to rotatably secure the shaftadjacent the second edge of the gap formed in the cylinder; means tosecure the saddle about a portion of the surface of a cylinder,saidsaddle having a seat formed in an edge thereof; hinge means torotatably secure said shaft in said seat; and resilient means securedbetween the shaft and the saddle, said resilient means being adapted tourge the connector means on the shaft into the gap formed in thecylinder.

4. The combination called for in claim 3.wherein the hinge means torotatably secure said shaft in saidseat comprises: a hinge elementhaving a 'bore' 'extending longitudinally therethrough; a pin onsaid'hinge-element extending into a socket formed in said seat-in thesaddle; and a spring positionable about said shaft-,one end of saidspring being secured to said hinge element and the other end of saidspring being secured to said shaft. l w

5. A printing press cylinder comprising: a cylinder; a printing platehaving leadingand trailing edges; a first flange on said leading edge; asecondflange on said; trailing edge, each.of said flanges having a row,of aper tures formed therein; spaced pegs secured to said cylinder saidpegs extending through apertures. in said first flange on the leadingedge of the printing plate; a shaft; hinge means rotatably securingopposite ends of'said' shaft to said cylinder; torsion spring meansaboutjea'ch end of said shaft; means securing first ends of each of saidtorsion springs to said cylinden'means securing second end of saidtorsion springs to said shaft; and spaced pins on said shaft positionedthrough apertures in said second flange on the trailing edge of saidprint ing plate, said torsion springs urging said pins ma posi tionwherein the printing plate is drawn to a controlled tension about saidcylinder. i

6. Apparatus to secure a printing plate about the surface of a cylindercomprising: a saddle'havin'g first and second edges and a seat formed ina first edge thereof; means to secure the saddle about a portionofthe-surface of the cylinderaspaced hinge elements; each of. said hingeelements having a boremextending therethrough; means securingsaid-hingeelem-entsadjacent said first edge of said saddle; a shaft,havingopposite ends rotatably secured in said bores in said hinge elements, said shaft extending longitudinally of said seat; a springpositioned about said shaft; meanssecuring. one end of said spring toone ofsaid hinge elements; means securing a second end of said spring tosaid shaft; means to secure a first edge of the printing'plate to saidshaft; and meansto secure a s econd edge of the printing plate adjacentsaid 'second edge of said saddle.

1. Apparatus to secure a printing plate having apertures formed inflanges on leading and trailing edges thereof to a cylinder having alongitudinally extending gap formed therein comprising: spaced pegssecured adjacent a first edge of the gap formed in the cylinder; ashaft; connector pins on said shaft positionable in apertures in theflange on the trailing edge of the printing plate; means to rotatablysecure the shaft adjacent the second edge of the gap formed in thecylinder; and resilient means secured between the shaft and the means torotatably secure the shaft to the cylinder, said resilient means beingadapted to urge the connector pins on the shaft into the gap formed inthe cylinder.
 2. The combination called for in claim 1 wherein the meansto rotatably secure the shaft to the cylinder comprises: a hinge elementhaving a bore extending therethrough; and means to secure said hingeelement to the cylinder, and wherein the shaft has a journal formed onthe end thereof; a shoulder adjacent said journal, said journal beingpositioned in the bore in the hinge element such that the shoulder onthe shaft engages said hinge element to limit longitudinal movement onthe shaft relative to hinge element.
 3. Apparatus to secure a printingplate to a cylinder having a longitudinally extending gap formed thereincomprising: means to secure a first edge of a printing plate adjacent afirst edge of the gap formed in the cylinder; a shaft; connector meansto secure a second edge of a printing plate to said shaft; a saddle torotatably secure the shaft adjacent the second edge of the gap formed inthe cylinder; means to secure the saddle about a portion of the surfaceof a cylinder, said saddle having a seat formed in an edge thereof;hinge means to rotatably secure said shaft in said seat; And resilientmeans secured between the shaft and the saddle, said resilient meansbeing adapted to urge the connector means on the shaft into the gapformed in the cylinder.
 4. The combination called for in claim 3 whereinthe hinge means to rotatably secure said shaft in said seat comprises: ahinge element having a bore extending longitudinally therethrough; a pinon said hinge element extending into a socket formed in said seat in thesaddle; and a spring positionable about said shaft, one end of saidspring being secured to said hinge element and the other end of saidspring being secured to said shaft.
 5. A printing press cylindercomprising: a cylinder; a printing plate having leading and trailingedges; a first flange on said leading edge; a second flange on saidtrailing edge, each of said flanges having a row of apertures formedtherein; spaced pegs secured to said cylinder, said pegs extendingthrough apertures in said first flange on the leading edge of theprinting plate; a shaft; hinge means rotatably securing opposite ends ofsaid shaft to said cylinder; torsion spring means about each end of saidshaft; means securing first ends of each of said torsion springs to saidcylinder; means securing second end of said torsion springs to saidshaft; and spaced pins on said shaft positioned through apertures insaid second flange on the trailing edge of said printing plate, saidtorsion springs urging said pins to a position wherein the printingplate is drawn to a controlled tension about said cylinder.
 6. Apparatusto secure a printing plate about the surface of a cylinder comprising: asaddle having first and second edges and a seat formed in a first edgethereof; means to secure the saddle about a portion of the surface ofthe cylinder; spaced hinge elements; each of said hinge elements havinga bore extending therethrough; means securing said hinge elementsadjacent said first edge of said saddle; a shaft having opposite endsrotatably secured in said bores in said hinge elements, said shaftextending longitudinally of said seat; a spring positioned about saidshaft; means securing one end of said spring to one of said hingeelements; means securing a second end of said spring to said shaft;means to secure a first edge of the printing plate to said shaft; andmeans to secure a second edge of the printing plate adjacent said secondedge of said saddle.